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Taiga Biomes - Blue Planet Biomes: Taiga

Now, another perspective. I originally wrote this post in the Pacific Northwest, a region noted for trees that are green all year round. Many trees, however, are not evergreen; they are deciduous. As you can see in this photograph from my winter home in Minnesota, they drop their leaves during the winter and go for several months at a stretch without any possibility of photosynthesis. How do deciduous trees and bushes get the energy they need to maintain life during the winter? Just as they do on a summer’s night. When their leaves are gone, deciduous trees rely on cellular respiration, disassembling the reserves of sugar (mainly in the form of starch stored in the roots) that they accumulated during the bright days of the year. They use this stored energy to drive all the diverse processes of life. A bear stores fat for the winter, a plant stores starch. And, as we will see in another post, in really cold weather both of them can reduce their demands for metabolic energy, and thus for food, dramatically.

While its trees have their leaves, a deciduous forest, like an evergreen forest, reverses its breath on a daily cycle. During the day, while photosynthesis works faster than does cellular respiration, a deciduous forest primarily breathes in carbon dioxide and exhales oxygen. During the night, when photosynthesis stops but cellular respiration continues unabated (not only in green plants but also in the myriad other organisms that compose the forest ecosystem), the forest breathes in oxygen and exhales carbon dioxide. Once the leaves are gone, however, it only breathes in oxygen. At that point, it no longer matters whether it’s day or night—the trees respire without photosynthesizing. They always take in oxygen and release carbon dioxide, just like you and I do.

Taiga Biome - KDE Santa Barbara

If we look a bit more carefully, however, we will see that plant photosynthesis and respiration are actually not entirely separated by the daily light/dark cycle—during the daytime they coexist. Remember, photosynthesis only takes place where there is chlorophyll, i.e. in the green cells of the leaves or needles. What about the rest of the plant—the stems, the roots, all the living cells that do not contain chlorophyll? They get sugar from the chlorophyll-containing cells. In fact, even the cells that photosynthesize also respire! You might say that the plant feeds itself the food that it itself has made, so that every one of its living cells can generate metabolic energy day and night without interruption.

With no photosynthesis, not only is no oxygen being released, but also no sugar is being made and no new stores of transformed solar energy are being generated. Nonetheless, the trees, bushes, and the delicate greenery of the understory all require an uninterrupted supply of metabolic energy to sustain their lives. Where does this energy come from? From the sugar these same plants made during the daytime and stored within their cells, either as the original sugar or as starch, a more compact form of energy storage. To access this stored energy, the plants use oxygen and release carbon dioxide. In short, they carry out cellular respiration pretty much like animals do. The entire cycle of photosynthesis and respiration takes place within the body of each green plant. The plant breathes in carbon dioxide and exhales oxygen during the day, and then does the opposite—breathes in oxygen and exhales carbon dioxide—during the night.

The Importance of Trees - Learn Value and ..

N2 - • Here we explore the possible role of leaf-level gas exchange traits in determining growth rate differences and competitive interactions between evergreen angiosperms and conifers. • We compared relationships among photosynthetic capacity (Amax), maximum stomatal conductance (G s), leaf life span, nitrogen concentration (N) and specific leaf area (SLA), in sun leaves of 23 evergreen angiosperm and 20 conifer populations. • Despite similar average leaf Nmass, conifer leaves lived longer on average (36 months) than angiosperms (25 months). At a standardized leaf N, Amass was higher in angiosperms (56 nmol g-1 s-1) than in conifers (36 nmol g-1 s-1). Stepwize regression suggested that most of this difference in photosynthetic nitrogen use efficiency could be explained by Gs and SLA. Mean G s (on an area basis) of angiosperms was higher than that of conifers (152 vs 117 mmol m2 s-1), but Aarea-G s relationships were similar for the two groups. At a given leaf N, conifers had lower SLA (projected area basis) than angiosperms. • Photosynthetic differences probably contribute to the competitive advantage of angiosperm trees over conifers in productive habitats, and may be linked to the greater hydraulic capacity of vessels, enabling angiosperms to develop higher stomatal conductance and therefore sustain higher transpiration rates.

Garden - How To Information | eHow

The Mondell pine tree is also known as the Afghan pine

• Here we explore the possible role of leaf-level gas exchange traits in determining growth rate differences and competitive interactions between evergreen angiosperms and conifers. • We compared relationships among photosynthetic capacity (Amax), maximum stomatal conductance (G s), leaf life span, nitrogen concentration (N) and specific leaf area (SLA), in sun leaves of 23 evergreen angiosperm and 20 conifer populations. • Despite similar average leaf Nmass, conifer leaves lived longer on average (36 months) than angiosperms (25 months). At a standardized leaf N, Amass was higher in angiosperms (56 nmol g-1 s-1) than in conifers (36 nmol g-1 s-1). Stepwize regression suggested that most of this difference in photosynthetic nitrogen use efficiency could be explained by Gs and SLA. Mean G s (on an area basis) of angiosperms was higher than that of conifers (152 vs 117 mmol m2 s-1), but Aarea-G s relationships were similar for the two groups. At a given leaf N, conifers had lower SLA (projected area basis) than angiosperms. • Photosynthetic differences probably contribute to the competitive advantage of angiosperm trees over conifers in productive habitats, and may be linked to the greater hydraulic capacity of vessels, enabling angiosperms to develop higher stomatal conductance and therefore sustain higher transpiration rates.

It is a relatively small pine that only grows to 30 or 40 feet

We considered as well the process of cellular respiration. In respiration, sugar molecules are disassembled, and the energy that was stored in them when they were synthesized is now used to carry out many life processes, including the contraction of muscles; the various electrical activities of nerve cells; and the construction of the complex molecules of which living cells are composed, such as proteins, fats, complex carbohydrates, and DNA. In these processes oxygen is used and carbon dioxide is released, only to be reused in photosynthesis.

Why trees shed their leaves | Earth | EarthSky

AB - • Here we explore the possible role of leaf-level gas exchange traits in determining growth rate differences and competitive interactions between evergreen angiosperms and conifers. • We compared relationships among photosynthetic capacity (Amax), maximum stomatal conductance (G s), leaf life span, nitrogen concentration (N) and specific leaf area (SLA), in sun leaves of 23 evergreen angiosperm and 20 conifer populations. • Despite similar average leaf Nmass, conifer leaves lived longer on average (36 months) than angiosperms (25 months). At a standardized leaf N, Amass was higher in angiosperms (56 nmol g-1 s-1) than in conifers (36 nmol g-1 s-1). Stepwize regression suggested that most of this difference in photosynthetic nitrogen use efficiency could be explained by Gs and SLA. Mean G s (on an area basis) of angiosperms was higher than that of conifers (152 vs 117 mmol m2 s-1), but Aarea-G s relationships were similar for the two groups. At a given leaf N, conifers had lower SLA (projected area basis) than angiosperms. • Photosynthetic differences probably contribute to the competitive advantage of angiosperm trees over conifers in productive habitats, and may be linked to the greater hydraulic capacity of vessels, enabling angiosperms to develop higher stomatal conductance and therefore sustain higher transpiration rates.